单项选择题
A.the shape of an unlighted buoy B.the light color of a lighted buoy C.the color of the topmost band D.whether the number is odd or even
A.Errors due to unusual parallax are eliminated B.The same body can be used for a fix from observations separated by several minutes C.The declination is the only information needed from the almanac D.The semidiameter correction of the sextant altitude is eliminated
A.Group flashing B.Composite group flashing C.Interrupted quick flashing D.Fixed and flashing